Cocaine use is still prevalent nationwide and effective treatment for cocaine dependence remains a challenge. Many factors have been implicated in drug dependence, including stress, impulsivity and sex differences. Our first assumption is that there is a reciprocal relationship between impulsivity and cocaine use. We will examine if impulsivity is a consequence of cocaine use by obtaining multiple measure of impulsivity after smoked cocaine administration under controlled laboratory conditions. Further, we will determine if impulsivity is a predictor of cocaine use by relating self-report measures of impulsivity to the amount of smoked cocaine self-administered under controlled laboratory conditions. Our second assumption is that stress modulates cocaine use. We will examine the effect of a physical and a psychological stressor on the choice to self-administer smoked cocaine under controlled laboratory conditions. Our third assumption, and an underlying theme throughout, is that sex is a modulating factor in the relationship between impulsivity, stress and cocaine use. We will determine differences in impulsivity and stress between cocaine-dependent men and women not seeking treatment for their cocaine use. In Study 1, we will determine if cocaine administration increases behavioral measures of impulsivity. Participants will perform various behavioral impulsivity tasks before and after smoking fixed doses of cocaine. In Study 1, we will also determine if scores on three impulsivity self-report measures predict or correlate with choice to self-administer smoked cocaine. Finally, as a link to Study 2, Study 1 will explore whether fixed doses of smoked cocaine alter various subjective stress responses. In Study 2, we will determine whether exposure to a psychological laboratory stressor (Trier Social Stress Test) and a physical laboratory stressor (Cold Pressor Test) increases cocaine self-administration. Participants will have the opportunity to smoke five doses of cocaine immediately after stress exposure;a No Stress condition will serve as a control. Studies 1 and 2 will be conducted in non-treatment seeking cocaine-dependent men and women, to directly address sex differences in stress and impulsivity. These data collected using human laboratory models will have direct implications for developing differential treatment strategies targeting impulsive behavior, stress reduction, and gender-specific treatment issues.